Correlation radii from A FAST HADRON FREEZE-OUT GENERATOR. ( FASTMC ). R. Lednicky: Joint Institute for Nuclear Research, Dubna, Russia I.P. Lokhtin, A.M. Snigirev , L.V. Malinina : Moscow State University, Institute of Nuclear Physics, Russia
Correlation radiifromA FAST HADRON FREEZE-OUT GENERATOR
( FASTMC )
R. Lednicky: Joint Institute for Nuclear Research, Dubna, Russia
I.P. Lokhtin, A.M. Snigirev , L.V. Malinina: Moscow State University, Institute of Nuclear Physics, Russia
Iu.A. Karpenko,Yu.M. Sinyukov: Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine
The predictions for correlation radii in the central Pb+Pb collisions for LHC GeV
(PRC 74 064901(2006))
1. Introduction- motivation.
2. Model parameters.
3. Physical framework of the model .
4. Predictions for LHC
- Various parameterizations of the hadron freeze-out hypersurface and flow velocity
- The C++ generator code is written under the ROOT framework.
Model parameters for central collisions:
Physical framework of the model: Hadron multiplicities
1.We consider the hadronic matter created in heavy-ion collisions as a hydrodynamically expanding fireball with the EOS of an ideal hadron gas.
2. “concept of effective volume” T=const and µ=const the total yield of particle species is: , total co-moving volume, ρ-particle number density
3.Chemical freeze-out : T, µi = µB Bi + µS Si + µQ Qi ; T, µB –can be fixed by particle ratios, or by phenomenological formulas
4. Chemical freeze-out: all macroscopic characteristics of particle system are determined via a set of equilibrium distribution functions in the fluid element rest frame:
Physical framework of the model: Thermal freeze-out
2. Assumption of the conservation of the particle number ratios in between the chemical and thermal freeze-out :
3. In the Boltzmann approximation:
Particles (stable, resonances) are generated on the thermal freeze-out hypersurface, the hadronic composition at this stage is defined by the parameters of the system at chemical freeze-out
Physical framework of the model: Hadron momentum distribution
We suppose that a hydrodynamic expansion of the fireball ends by a sudden system breakup
at given T and chemical potentials. Momentum distribution of produced hadrons keeps
the thermal character of the equilibrium distribution.
1. The Bjorken model with hypersurface
2. Linear transverse flow rapidity profile:
3. The total effective volume for particle production at
Predictions for LHC
We considered the naive ``scaling'' of the existingphysical picture of heavy ion interactions over two order ofmagnitude in to the maximal LHC energy
- FASTMCfitting of theexisting experimental data onmt-spectra, particle ratios, rapidity densitydN/dy, kt-dependence of the correlation radiifrom
SPS (= 8.7 - 17.3GeV)to RHIC (= 200GeV)
-The linear extrapolation of the model parametersin to LHC
For LHC energies we have fixed the thermodynamic parameters at chemical freeze-outas the asymptotic ones:Tch=170MeV,µB=0, µS=0, µQ=0 MeV.
Predictions for LHC
SPS (= 8.7 - 17.3GeV)
▲RHIC (= 200GeV)
LHC ( = 5500 GeV)
Predictions for LHC: Conclusions
The extrapolated values :
R ~ 11fm, τ ~ 10fm/c, Δτ~ 3.0fm/c,
~ 1.0, Tth ~ 130MeV.
Tch=170MeV,µB=0, µS=0, µQ=0 MeV
dN/dy ~ 1400 twice larger than at RHIC
in coincidence with the naive
extrapolation of dN/dy.
These parameters yield only a small
increase of thecorrelation radii
Rout, Rside, Rlong